1. Field of the Invention
The present invention relates to an apparatus for connecting electronic appliances, a control apparatus and an address setting method suitable for collectively controlling a plurality of electronic appliances such as audio visual appliances or the like.
2. Description of the Prior Art
In a data transmission system according to the RS-232C standard, it is known that operation of audio and visual appliances (hereinafter simply referred to as AV appliances) can be controlled by a computer, such as a personal computer or the like.
According to the RS-232C standard, various data are transmitted and received in a manner so that the computer and the AV appliances are placed in a one-to-one relation. Therefore, in the case of a system in which a plurality of AV appliances are controlled by a single computer (control apparatus), the computer side must include an RS-232C standard terminal corresponding to each of the AV appliances, or special change-over switches for switching the data transmission to the respective AV appliances must be employed. Accordingly, there is then the problem that the system cannot be used well for various purposes because the number of terminals or the switching ability of the change-over switches (the number of the change-over switches) must be changed with the increase or decrease of the AV appliances.
It is also proposed that a plurality of AV appliances can be controlled by utilizing a bus line used in a so-called local network system. This proposal, however, has the following disadvantages. For example, when two or more different data are simultaneously transmitted, detection of such data becomes complicated (troublesome) and the transmission processing of such data also becomes complicated, which unavoidably makes the interface housed within the AV appliance large-sized and expensive.
Further, it is conventional to connect a plurality of controlled apparatus (electronic appliances such as AV appliances) in series (in a daisy chain fashion) to a control apparatus such as a controller or the like. The respective AV appliances are controlled in operation by this controller. In such a system, addresses are allocated (set) to the respective AV appliances and a command signal for commanding operation of the particular AV appliance is transmitted to the particular AV appliance together with the address from the controller. Accordingly, addresses to allocated to the respective AV appliances must be made different.
In order to remove this disadvantage, it is proposed that addresses are allocated to different categories of AV appliances (e.g., categories of television receiver, a video tape recorder, a television camera and so on). This proposal, however, has the disadvantage that, if two video tape recorders are provided, then addresses for identifying these two video tape recorders cannot be allocated.
It has also been proposed that respective AV appliances be provided with dip switches or the like, so that addresses can be set by manipulating the dip switches. However, this proposal makes the arrangement of the AV apparatus complicated and addresses must be set in a manual fashion. As a consequence, if the number of AV appliances is increased, then the addressing setting becomes considerably troublesome.